This project seeks to characterize the effects of hemorrhagic shock on glucose homeostasis. Previous results indicated that animals with mitochondrial dysfunction during shock maintained their blood glucose concentration at the expense of their hepatic glucogen reserves. This investigation seeks to relate shock-induced alterations in hepatic mitochondrial energy-linked functions with failure of subcellular aspects of gluconeogenesis. Phosphoenolpyruvate (PEP) synthesis was measured in mitochondria isolated from guinea pigs subject to hemorrhagic shock. Shocked animals with impaired mitochondrial energy-linked functions had a significant (p less than .01) decrease in ability to synthesize PEP. Shocked animals that maintained mitochondrial energy-linked functions also maintained PEP synthesis similar to that of non-shocked controls. When ADP was substituted for ATP the amounts of PEP synthesized in each group were similar to those observed with ATP. The decreased PEP synthesis in animals with impaired mitochondrial function was again significant (p less than .001) but the percent decrease was greater with ADP than ATP. When ATP or ADP was eliminated there was a marked decrease in PEP synthesis in all groups but particularly in shocked animals with impaired mitochondrial function. These studies support the hypothesis that decreased gluconeogenesis in late hemorrhagic shock is secondary to defective high-energy phosphate production.